• Journal of Ocean Engineering and Technology
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• v.17 no.4
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• pp.73-80
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• 2003

This paper presents considerations on the results of the rotating arm test, which was carried out for assessment of an hybrid navigation system for a semi-autonomous underwater vehicle. The navigation system consists of an inertial measurement unit(IMU), an ultra-short baseline(USBL) acoustic navigation sensor and a doppler velocity log(DVL) accompanying a magnetic compass. A navigational systemmodel is derived to include the scale effect and bias errors of the DVL, of which the state equation composed of the navigation states and sensor parameters are 25 in the order. The extended Kalman filter was used to propagate the error covariance, The rotating arm tests were carried out in the Ocean Engineering Basin of KRISO, to generate circular motion. The hybrid underwater navigation system shows good tracking performance against the circular planar motion. Additionally this paper checked the effects of the sampling ratio of the navigation system and the possibility of the dead reckoning with the DVL and the magnetic compass to estimate the position of the vehicle.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.57-63
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• 2002

In this paper, the feedforward control with least mean square (LMS) adaptive algorithm is proposed and examined to reduce rotating error by runout of an active magnetic bearing system. Using eddy-current type gap sensor fur control, the electrical runout caused by non-uniform material properties of sensor target produces rotational error amplified in feedback control loop, so this runout should be eliminated to increase rotating accuracy. The adaptive feedforward controller is designed and examined its tracking and stability performances numerically with established frequency response function. The tested grinding spindle system is manufactured with a 5.5 ㎾ internal motor and 5-axis active magnetic bearing system including 5 eddy current gap sensors which have approximately 15 ~ 30 ${\mu}{\textrm}{m}$ of electrical runout. According to the experimental analysis, the error signal in radial bearings is reduced to less than 5 ${\mu}{\textrm}{m}$ when it is rotating up to 50,000 rpm due to applying the feedforward control for first order harmonic frequency, and vibration of the spindle base is also reduced about same frequency.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.107-109
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• 2005

This paper presents the development of the magnetic position sensor for servo motor. The magnetization system is designed for the sinusoidal magnetic flux density distribution from permanent magnet using 2D finite element method and Preisach model. The magnetic position sensor is composed of the permanent magnet and two Hall elements. And the algorithm calculating the rotating position is suggested by the phase difference of outputs of Hall elements.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1105-1109
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• 1995

A CCD-camera, which is structured with vision system, was used to realize automatic seam-tracking system and 3-D information which is needed to generate torch path, was obtained by using laser-slip beam. To extract laser strip and obtain welding-specific point, Adaptive Hough-transformation was used. Although the basic Hough transformation takes too much time to process image on line, it has a tendency to be robust to the noises as like spatter. For that reson, it was complemented with Adaptive Hough transformation to have an on-line processing ability for scanning a welding-specific point. the dead zone,where the sensing of weld line is impossible, is eliminated by rotating the camera with its rotating axis centered at welding torch. The camera angle is controlled so as to get the minimum image data for the sensing of weld line, hence the image processing time is reduced. The fuzzy controller is adapted to control the camera angle.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.34-38
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• 2020

In this paper, we implement a Dashcam system capable of shooting 360 degrees using a Raspberry Pi, shock sensors, distance sensors, and rotating camera with a servo motor. If there is an object approaching the vehicle by the distance sensor, the camera rotates to take a video. In the event of an external shock, videos and images are stored in the server to analyze the cause of the vehicle's accident and prevent the user from forging or tampering with videos or images. We also implement functions that transmit the message with the location and the intensity of the impact when the accident occurs and send the vehicle information to an insurance authority with by linking the system with a smart device. It is advantage that the authority analyzes the transmitted message and provides the accident handling information giving the user's safety and convenience.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.770-772
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• 2002

In this paper, the eddy current sensor is develped for observing the ability of detecting defect with variation of frequency and velocity. The circuit designed for processing detected voltage and changing frequency is used for eddy current sensor to detect defect with variation of frequency. The ability of eddy current sensor to detect defects is studied with variation of velocity adjusted by rotating the circular plate. This study shows that the ability of eddy current sensor for detecting defect is increased and decreased by frequency. This fact means that the sensor has its best ability at a certain frequency. And the ability of eddy current sensor by velocity is decreased by increased velocity. Therefore, the eddy current sensor has to be developed with consideration of its operation velocity and frequency.

• Proceedings of the KWS Conference
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• 2002.05a
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• pp.46-48
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• 2002

• Journal of Welding and Joining
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• v.24 no.1
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• pp.7-9
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• 2006

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1087-1090
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• 2007

A wireless magnetic torque sensor is utilized to measure the torque generated in the rotating shaft in magnetic field without connecting to the shaft by any wire. In this study, a new wireless magnetic torque sensor was introduced. The structure of the sensor was explained detailed as well as its operation principle. Resulting from the torque measurement experiment results, the sensor was proven to measure the generated torque effectively. Compared with traditional contact torque sensor, the wireless one has low cost and good environment adaptation ability. Moreover, the intractable wrapping wires around the shaft are removed in this design. Hence the wireless torque sensor may be expected as a possible sensing device for many applications, such as the electric assisting rotation system in automobiles, the torque sensing system in motors, the arm rotation system in robotics and so on.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.143-146
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• 2006

In this paper, a hybrid sensor is proposed that has two capabilities: The first is to sense longitudinal of flexural elastic waves selectively which are transmitted along the targe shaft, the second to measure the rotating speed of the shaft. All measurement are made in a noncontact manner since this sensor uses magnetostriction as its measuring principles. Furthermore, the switching between these two sensing capabilities are accomplished by a very simple mechanical operation. To verify the capabilities of the Proposed sensor, an Prototype sensor are fabricated and the experiments are made. The result shows this sensor can embody two sensing capabilities in one sensor configuration.